Cheers,
I like strict typing in C. Therefore, I don't want to store a 2D vector of floats if I specifically need integers. Is there an Apple-provided equivalent of CGPoint which stores data as integers?
I've implemented my type Vector2i and its companion function Vector2iMake() à la CGPoint, but something deep in me screams that Apple was there already.
Updating to explain.
I need a datatype that will store coordinates in a board game. These are most definitely integers. Same would be if I were to implement a tile-based turn based strategy, or a tile-based RPG.
(to directly answer the question...)
I am not aware of a "NSIntegerPoint", but it wouldn't be difficult to make one:
struct NSIntegerPoint {
NSInteger x;
NSInteger y;
};
Along with stuff like:
CG_INLINE NSIntegerPoint
NSIntegerPointMake(NSInteger x, NSInteger y)
{
NSIntegerPoint p; p.x = x; p.y = y; return p;
}
CG_INLINE bool
__NSIntegerPointEqualToPoint(NSIntegerPoint point1, NSIntegerPoint point2)
{
return point1.x == point2.x && point1.y == point2.y;
}
#define NSIntegerPointEqualToPoint __NSIntegerPointEqualToPoint
If you happen to be representing your game board as objects stored in non-sparse nested arrays, then you may want to consider subclassing NSIndexPath, or using it directly.
From the class reference:
The NSIndexPath class represents the path to a specific node in a tree of nested array collections. This path is known as an index path.
Each index in an index path represents the index into an array of children from one node in the tree to another, deeper, node.
According to iPhone Application Programming Guide, all provided points are float-based. And when you use them to work with the screen (eventually expecting integers), you should anyway use floats for independence from screen resolution and etc.
You could use int vectors?
http://developer.apple.com/mac/library/documentation/Performance/Conceptual/vecLib/Reference/reference.html#//apple_ref/doc/uid/TP40002498-CH1g-TPXREF103
Related
There is no simd_packed_float3 type in Swift.
Why it's a problem?
Consider this Metal struct:
struct Test{
packed_float3 x;
float y;
};
First of all, you can't calculate a buffer pointer to address the memory of y, since you can't do this:
MemoryLayout<simd_packed_float3>.size
(Not sure if stride makes sense with packed types, but anyway with simd types it always gives the same length as size on my devices)
You can't use MemoryLayout<simd_float3>.size either, since it will return 16 and not 12 like in architectures available to me for testing.
Second, if you need to write a packed_float3 value of x to the buffer you will need to write the three consecutive floats, but not a single simd type. Again, simd_float3 is not usable since it will write 0 into the forth word corrupting the memory of the next property in the struct (y).
So I've done this:
struct Float_3{
var x: Float
var y: Float
var z: Float
}
typealias simd_packed_float3 = Float_3
It seems to be a functioning solution, but I'm not sure it's not a nasty thing to do...
What problems may I encounter with this approach, and how could I be sure that it won't break on some device that I don't have?
You can define a packed struct in your bridging header:
struct __attribute__((packed)) PackedFloat3 {
float x;
float y;
float z;
};
MemoryLayout<PackedFloat3>.size == 12
MemoryLayout<PackedFloat3>.stride == 12
By the way, simd_float3 is 16 bytes everywhere, simd types have stricter alignment requirements.
You can also typedef it to packed_float3 under #ifndef #ifdef __METAL_VERSION__ to have the same spelling in Swift and MSL.
The reason to do it in bridging header instead of Swift is that you can use the same structs with same spelling in both shaders and Swift.
I'm answering this following the answers I received on the Swift forum.
Turns out that someone in the Metal team at Apple has already thought of this problem and created the MTLPacked types exactly for the types that would have irregular sizes:
MTLPackedFloat3
MTLPackedFloat4x3
I have a non-geographic map aka flat image using CRS.Simple extended by a custom transformation. Everything works fine so far, but now I want to add a distance measurement button. I'm confident I could implement a distance measurement between two markers myself, but the dynamic line drawing and measuring is still a bit above my skills, so I hoped I could use a plugin. None of the ones I found, did offer this though. After looking at the plugins page of leaflet, I tried this fork https://github.com/aprilandjan/leaflet.measure of leaflet.measure originally by https://github.com/jtreml/leaflet.measure as it seemed to offer the ability to add custom units - in my case pixels.
I added this:
L.control.measure({
// distance formatter, output mile instead of km
formatDistance: function (val) {
return Math.round(1000 * val / scaleFactor) / 1000 + 'mapUnits';
}
}).addTo(map)
Unfortunately, the result is a number far too big compared to the pixelsize of the map (4096x4096). distance() returns the expected 1414.213562373095 between a point 1000,1000 and one at 2000,2000. Calculating distanctTo returns 8009572.105082839 instead though. I use this at the beginning of my file
var yx = L.latLng;
var xy = function(x, y) {
if (L.Util.isArray(x)) { // When doing xy([x, y]);
return yx(x[1], x[0]);
}
return yx(y, x); // When doing xy(x, y);
};
If I log val to the console, I get things like this:
20411385.176805027
7118674.47741132
20409736.502863288
7117025.8034695815
20409186.004645467
20409736.502863288
That's likely some problem of the function trying to calculate latlng without a proper reference system.
Anyone got an idea how to solve this? I feel like it can't be overly difficult, but I don't know exactly where to start.
I found a way to do it, even though it feels a bit 'hacky':
I replaced the line
var distance = e.latlng.distanceTo(this._lastPoint)
in the _mouseMove and the _mouseClick events of leaflet.measure with
var currentPoint = e.latlng;
var lastPoint = this._lastPoint;
var distance = map.distance(currentPoint, lastPoint);
as the distance() method of the map returns meters, or in the case of a flat image, pixel values. And those we can translate in whatever unit we want in our flat image.
If anyone has a more elegant way, I'm all ears!
I'm confused about the coordinate.column and coordinate.row used in the code swift plyground provided below. How was column and row accssed when I didn't instantiate the instance coordinate? If the for loop insatntiate coordinate, how was it instantiated when allcoordinates or world.allPossibleCoordinates are not a type? (There are no parathenthesis around world.allPossibleCoordinates...)
let allCoordinates = world.allPossibleCoordinates
var blockSet: [Coordinate] = []
//#-editable-code Tap to enter code
for coordinate in allCoordinates {
// Check for coordinates with a column > 5 OR a row < 4.
if coordinate.column > 2 && coordinate.row < 5 {
// Append coordinate to blockSet.
}
}
In Swift, the for in loop works a bit differently than a for loop in other languages. A for in loop strides over a range (I'm assuming allCoordinates is strideable). In the provided example, if the variable allCoordinates is a strideable range, the loop will go through every single item in that range assigning each value to coordinate per iteration. For more information, have a look at Apple's Documentation
I need help with making an if/then statement which depends on a movie clip being between a certain set of coordinates for the rule to work. Here is the code I tried to use:
if (honey1.x >=165 <=231.x;
honey1.y >=295 <=330.y;) {
honeyOne = true}
}
I haven't had much luck finding a lot of help on condition statements beyond very simple or unrelated notes. If anyone knows how to make a statement like this work, I would be most appreciative.
A method to test that a number is between two bounds might look like this.
bool IsBetweenInclusive(int value, int lower, int upper)
{
return value >= lower
&& value <= upper;
}
That's easily extendable to a point structure
bool IsBetweenInclusive(Point value, Point lower, Point upper)
{
return IsBetweenInclusive(value.X, lower.X, upper.X)
&& IsBetweenInclusive(value.Y, lower.Y, upper.Y);
}
If your coordinate system is in a double or float kind of number space, you'll need to do work to account for rounding.
hey guys i want your suggestion that how can change value of two variables without 3rd one. in objective cc.
is there any way so please inform me,
it can be done in any language. x and y are 2 variables and we want to swap them
{
//lets say x , y are 1 ,2
x = x + y; // 1+2 =3
y = x - y; // 3 -2 = 1
x = x -y; // 3-1 = 2;
}
you can use these equation in any language to achieve this
Do you mean exchange the value of two variables, as in the XOR swap algorithm? Unless you're trying to answer a pointless interview question, programming in assembly language, or competing in the IOCCC, don't bother. A good optimizing compiler will probably handle the standard tmp = a; a = b; b = tmp; better than whatever trick you might come up with.
If you are doing one of those things (or are just curious), see the Wikipedia article for more info.
As far as number is concerned you can swap numbers in any language without using the third one whether it's java, objective-C OR C/C++,
For more info
Potential Problem in "Swapping values of two variables without using a third variable"
Since this is explicitly for iPhone, you can use the ARM instruction SWP, but it's almost inconceivable why you'd want to. The complier is much, much better at this kind of optimization. If you just want to avoid the temporary variable in code, write an inline function to handle it. The compiler will optimize it away if it can be done more efficiently.
NSString * first = #"bharath";
NSString * second = #"raj";
first = [NSString stringWithFormat:#"%#%#",first,second];
NSRange needleRange = NSMakeRange(0,
first.length - second.length);
second = [first substringWithRange:needleRange];
first = [first substringFromIndex:second.length];
NSLog(#"first---> %#, Second---> %#",first,second);